BPA对低温制备锐钛矿型TiO_2薄膜表面形貌的控制

Morphology Control of Anatase TiO_2 Films Prepared at Low Temperature Using 4,4′-isopropylidenediphenol

采用4,4′-二羟基二苯基丙烷(BPA)作为TiO2薄膜表面形貌控制的模板剂.将BPA的乙醇溶液与具有锐钛矿晶粒的TiO2溶胶均匀混合制得涂膜液,采用浸渍提拉法制备薄膜;用无水乙醇将薄膜中的BPA选择性溶解去除,实现了低温下锐钛矿型TiO2薄膜的制备及其表面形貌的调控.采用SEM考察了TiO2溶胶用量、BPA用量、以及无水乙醇用量等因素对TiO2薄膜表面形貌的影响,并对其控制机理进行了探讨.结果表明,涂膜液的组成会影响到湿膜烘干过程中粒子的迁移和聚集,从而改变TiO2与BPA在薄膜表面的分布状态,最终对TiO2薄膜的表面形貌产生影响.随BPA浓度的降低,其影响逐渐由薄膜内部转向薄膜的表面区域.而低TiO2胶粒浓度和高乙醇含量则有利于TiO2薄膜产生粗糙的形貌或多孔性的结构.

4,4＇-isopropylidenediphenol （BPA） was used as a template to control the surface morphology of TiO2 films. A solution was produced by evenly stirring the mixture of the BPA ethanol solution and the TiO2 sol containing anatase grains. The films was prepared from resultant solution by a dip-coating technique, and then the BPA was preferentially extracted by anhydrous ethanol. So the anatase TiO2 films were obtained at low temperature, and the control of the surface morphology of the films was also achieved. Scanning electron microscopy （SEM） was adopted to analyze the influence of the dosage of TiO2 sol, BPA, and the anhydrous ethanol on the morphology of the films, and the control mechanism was also discussed. The results showed that the composition of the solution could affect the move and the aggregation of particles in the drying process of wet films, and thus change the distribution of TiO2 and BPA on the surface of the films, and ultimately influence the surface structure of TiO2 films. With the decrease of BPA concentration, the effect region of BPA was changed from the inside region of the film to the surface region of the film. Low concentration of TiO2 colloidal particle and high content of ethanol were propitious to form rough morphology or porous structure.